An LCD display is mainly composed by three major parts of a display panel, a backlight module, and a driving circuit, the driving circuit includes a gate driving unit, a data driving unit, and other elements. When the LCD display operates, pixel cells on the display panel are scanned progressively by the gate driving unit, once one row is scanned, all pixel cells in this row will be turned on. For instance, the gate driving unit inputs a high level to gates of Thin Film Transistors (referred to as TFTs for short) of the pixel cells to thereby turn on the TFTs, and TFTs will be turned off when the gate driving unit inputs a low level to gates of the TFTs. When the TFTs are turned on, the data driving unit will write a data voltage to the pixel cells in the corresponding row, so that a voltage of the pixel cells is charged to a pixel voltage required to display an image, liquid crystal molecules of the pixel cells deflect by the action of an electric field, thereby light of a backlight source travels through the pixel cells to form an image.
However, in practice, TFTs located in different regions of the display panel are different in properties, this leads to unevenness of displaying of the display cells in different regions, for instance, a grayscale luminance or a flicker degree varies in a different region.